Microscopic image of a human embryo on the 14th day of development, implanted in the new artificial uterus.
Research has finally made it possible to observe one of the phases of fertilization least understood by science (the 12 to 14 days after fertilization).
Researchers developed, through bioengineering, an endometrial model to study processes as important as they are unknown to science, such as embryo implantation, which determines whether a pregnancy will continue or not, and the first communication with the mother.
Cell magazine described, in a scientific article on Tuesday, how the first artificial uterine lining was designed capable of responding to embryo implantation in the same way as a woman’s endometrium during pregnancy, producing the essential mechanisms to nourish it.
The work is the result of a collaboration between scientists from the Babraham Institute in Cambridge (United Kingdom) and Stanford University in the United States, reported the Efe agency. The developing embryo implants in the lining of the uterus (endometrium) one week after fertilization, and this marks the beginning of one of the least understood phases in science due to the difficulty of observing the embryo during and after implantation.
“Understanding embryo implantation and its subsequent immediate development has great clinical relevance, as these stages are particularly prone to failure, especially in in vitro fertilization procedures”, explained one of the authors, Peter Rugg-Gunn, a researcher at the Babraham Institute.
To achieve this understanding, Rugg-Gunn and her team were able to replicate in 3D the complex physiological properties and cellular composition of the uterine lining. Scientists isolated two essential types of cells from endometrial tissue donated by healthy individuals who underwent biopsies to artificially recreate this tissue: epithelial and stromal cells.
At the same time, they used information from donated tissue to identify the key components that give structure to the uterine lining.
The researchers were able to incorporate these components, along with the stromal cells, into a special type of gel to promote cell growth in a thick layer. They later added epithelial cells that spread over the surface of the stromal cells.
The artificial endometrium presented the same cellular architecture as the donated tissue and responded in the same way to hormonal stimulation, indicating that could be receptive to embryo implantationexplain the authors.
The team tested their model using early human embryos donated by people undergoing in vitro fertilization and found that the embryo went through the expected phases of adhesion and implantation in the artificial endometrium.
After implementation, the embryos have increased secretion of certain pregnancy-related proteins and the hormone human chorionic gonadotropin (hCG), used in pregnancy tests.
“Previous models had not achieved this, so this was a tremendous advance“, Rugg-Gunn highlighted in a statement.
The artificial endometrium promoted embryonic development after implantation, allowing researchers to analyze the early embryonic stages (12 to 14 days after fertilization), which were practically unexplored until then.
The researchers observed that embryos implanted in the artificial endometrium reached several developmental milestones, such as the appearance of specialized cell types and the establishment of others that are precursors to placental development.
The analysis of individual cells at implantation sites made it possible to discover the first “cellular communication” between the embryo and the endometrium, enabling the creation of the structures through which mother and child exchange oxygen and nutrients during pregnancy.
Better understanding this phase is key to finding answers about infertility, miscarriages and conditions like pre-eclampsia, Rugg-Gunn pointed out.
